Relationship between autonomic nervous system activity and bone mineral density in non-medicated perimenopausal women.

The autonomic nervous system (ANS) has attracted attention as a regulator of bone remodeling and the effects of beta-blockers on the prevention of osteoporosis have been studied. However, results are as yet inconclusive and the physiological role of the ANS in bone metabolism has not been clarified. Thus, we investigated the relationship between bone mineral density (BMD) and ANS activity in non-medicated perimenopausal women. ANS activity was evaluated by power spectral analysis of heart rate variability, and overall ANS activity and the balance between sympathetic and parasympathetic nervous activities (SNS and PNS) were quantified. Pre- and postmenopausal subjects were divided into higher or lower overall ANS activity groups, and were also divided into SNS- and PNS-dominant groups. BMD (percentage of young adult mean) was significantly higher in the higher overall ANS group than in the lower group (112.2 ± 16.2 % vs 99.7 ± 14.8 %, p < 0.05) of premenopausal subjects, but not in postmenopausal subjects (91.5 ± 15.9 % vs 91.0 ± 14.9 %). BMD was significantly higher in the SNS-dominant group than in the PNS-dominant group (94.1 ± 16.3 % vs 88.4 ± 18.8 %, p < 0.05) of postmenopausal subjects, but not in the premenopausal subjects (103.5 ± 18.4 % vs. 107.2 ± 14.6 %). Our study revealed that ANS influences bone metabolism under physiological conditions. Thus, it appears to be worthwhile to introduce ANS activity evaluation into the management of bone health in perimenopausal women.